Lighting installation for vehicles



y 1934. F. H. DE JONG 1,965,308

LIGHTING INSTALLATION FOR VEHICLES Filed Dec. 11, 1931 Patented July 3, 1934 UNITED STATES PATENT OFFICE LIGHTING INSTALLATION FOR VEHICLES Application December 11, 1931, Serial No. 580,462

In Germany January 6, 1931 8 Claims.

This invention relates to a lighting installation for vehicles, for instance railway cars, and may in general be used Where the speed of the supply dynamo is subject to strong variations.

During the periods of rest of the vehicle the current supply in such installations is usually eifected by means of a battery, and above a definite speed of the vehicle the current is sup plied by a generator, which is driven from the vehicle itself, for instance from one of the car axles or from the motor shaft, and which at the same time serves for charging the battery. How- ..ever, the difiiculty of keeping the tension at a constant value is always encountered, since the speed of the dynamo may vary within very wide limits during operation, so that the control device must satisfy high requirements.

The present invention has for its purpose to provide a train lighting system in which the tension of the generator may be kept constant in a simple manner, in spite of strong variations of the speed.

According to the invention the magnets of the dynamo are provided with two windings, one of which is directly connected to the mains, whereas the other winding, which counteracts the former, is fed by an auxiliary dynamo which either directly or through the intermediary of a transmission is likewise coupled with the car axle or motor shaft. The exciting current of the auxiliary dynamo is controlled by means of a thermionic governor.

The invention will be more clearly understood by reference to the accompanying drawing.

Figs. 1-4 are schematic diagrams of various installations according to my invention.

Fig. 1 represents diagrammatically a form of construction of the invention, in which G denotes the main dynamo, whose armature is mounted on 40 one of the rotary shafts. H designates the auxiliary dynamo, which as a rule is coupled with the main dynamo, and whose speed is subject to variations of equal strength. The main exciting winding 1 is connected through a resistance 4 to 45 the terminals of the main generator. This resistance is not essential and may often be omitted. The second or auxiliary exciting winding 2 is connected either directly or through a resistance to the terminals of the auxiliary 50 dynamo. The latter has an exciting winding 3 which may be connected to the terminals of the auxiliary dynamo or fed from an outer source of current, for instance, from a battery or from the main dynamo. The governor 5 will be described as hereinafter. This governor is influenced by the tension set up between the mains 7 as indicated by the lines 6.

The operation of the installation is as follows: Suppose the tension between the mains be constant, then the winding 1 has a constant number of ampere turns. In order to obtain a constant tension, care must be taken that the total number of ampere turns on the magnets of the main dynamo decreases rather strongly with the speed.

. The arrangement is such that at a comparatively small speed the tension of the main generator suffices. for supplying the required number of ampere turns for the field. With an increasing speed the tension set up at the terminals of G would also become too high, if the number of ampere turns remain the same. Since, however, the winding 2 counteracts the first winding, the field of the main dynamo will gradually weaken. If the field of the auxiliary dynamo were constant, then the number of counteracting ampere turns would increase lineally with the speed, thus obtaining that the tension is kept constant within definite limits. However, there remains certain differences which, it is true, are smaller than those occurring in devices without counteracting winding, but which may nevertheless have a rather considerable value. In order to compensate for them a thermionic governor is interposed in the exciting circuit of the auxiliary dynamo, this governor controlling the field of the auxiliary dynamo upon speed variations in such manner that the tension set up at the terminals of the main dynamo substantially remains constant. When using this control device only a small number of discharge tubes are required. It has been found, that when connecting the governor to the terminals of the main dynamo the tension may be kept substantially constant, whereas the speed varies within very wide limits.

Fig. 2 represents, by way of example, the coupling arrangement of the governor. One end of the exciting Winding 3 of the auxiliary dynamo is connected to one of the terminals of the main dynamo and the other end to the anode 9 of the diode 8. One pole of the cathode 10 of this diode is directly connected to the negative main and the other pole to the positive main through a resistance 11. Each voltage variation afiects the exciting current of the auxiliary dynamo in such manner that the variation is counteracted.

Fig. 3 shows a modified form of construction. This figure substantially corresponds to Fig. 2 but the diode 8 is replaced by a triode, whose grid is connected through a battery B to the slide contact of a potentiometer connected to the terminals of the generator. The battery voltage slightly exceeds the tension of the potentiometer set up at the grid and counteracts the latter so that the grid is negative with respect to the cathode. With an increase generator voltage the grid voltage increases in absolute value and this results in an increase of the anode current which also passes through the exciting winding 3. Consequently the tension of the auxiliary dynamo increases and the number of counteracting ampere turns of the auxiliary exciting winding 2 increases so that the variations of the generator voltage are counteracted. With this coupling arrangement the discharge tube works at the same time as diode governor. Of course, it is also possible to use a separate current source for feeding the cathode, in which case the tube works as triode governor only.

Fig. 4 shows another manner of connecting the triode. This arrangement is distinct from that shown in Fig. 3 in that the cathode is connected in series with the main exciting winding 1. In this case the tube also operates as a triode-and as a diode-governor. One advantage resides in the fact that the exciting winding 1 serves at the same-time as a series-resistance for the cathode so that the losses are reduced. In order to adapt the heating current to the exciting current a resistance may be connected in parallel with the cathode, though this is less desirable in many cases. A further advantage consists in that no undue voltage increase is produced if the filament is destroyed or if a short circuit occurs between the filament and the anode. In the first case the voltage will completely disappear, and in the second case the resistance in the exciting winding of the auxiliary dynamo acquires a minimum value so that the field of the main dynamo is counteracted as much as possible.

In many cases it is, of course, possible to connect a plurality of such diodes or triodes in parallel with each other.

What I claim is:

1. An electric installation comprising a main dynamo, having an exciting winding connected across the terminals of the said dynamo, a second exciting winding, an auxiliary dynamo mechanically coupled to said main dynamo and supplying the second exciting winding with current in such manner as to counteract the field, created by the first winding, an exciting circuit for the said auxiliary dynamo, at least one triode, containing an incandescent cathode, a grid and'an anode, said anode and cathode being inserted in said exciting circuit, a potentiometer device connected across the terminals of the main dynamo andhaving a sliding contact connected to the grid of the triode, means for biasing the grid of the triode, and one end of the potentiometer being connected to the cathode.

2. An electric installation comprising a main dynamo having an armature and an exciting winding connected across said armature, a second exciting winding, an auxiliary dynamo mechanically coupled to said main dynamo and energizing the second exciting windingin such manner as to counteract the field created by the first winding, at least one triode, containing an incandescent cathode, a grid and an anode, an exciting circuit for the auxiliary dynamo including the cathode and anode, and a potentiometer connected across the terminals of the main dynamo and having a sliding contact connected to the grid of the triode, means for biasing the to said main generator, an auxiliary field wind-.

ing for the main generator, differentially wound with respect to the main field winding and comprising the load for said auxiliary generator, 8. field winding for said auxiliary generator, and a thermionic device connected between the field winding for the auxiliary generator and the output of the main generator, with the cathode across said output, to increase the sensitivity of current flow through the auxiliary field winding in response to variations in output of the main generator.

4. An electrical installation for maintaining the voltage output of a variable speed generator substantially constant, comprising a main generator, a main field winding for said generator connected across the terminals of the generator, an auxiliary generator mechanically coupled to said main generator, an auxiliary field winding for the main generator, differentially wound with respect to the main field winding and comprising the load for said auxiliary generator, a field winding for said auxiliary generator connected across the output of said main generator, and a diode in the circuit of said field winding with its cathode connected across said output, to increase the sensitivity of current flow through the auxiliary field winding in response to variations in output of the main generator.

5. An electrical installation for maintaining the voltage output of a variable speed generator substantially constant, comprising a main generator, a main field winding for said generator, an auxiliary generator mechanically coupled to said main generator, an auxiliary field winding for the main generator, difierentially wound with respect to the main field winding and comprising the load for said auxiliary generator, a field winding for said auxiliary generator and connected across the output of said main generator, a resistor connected across said last-mentioned output, a triode connected in the circuit of said fieldwinding for the said auxiliary generator,

with itscathode connected across the output oi pole connected with the grid of said triode, to

increase the sensitivity of current flow through the auxiliary field winding in response to variations in output of the main generator.

' 6. An electrical installation for maintaining the voltage output of a variable speed generator substantially constant, comprising a main generator, a main field winding for said generator, an auxiliary generator mechanically coupled to said main generator, an auxiliary field winding for the main generator, differentially wound with respect to the main field winding and comprising the load for said auxiliary generator, a field winding for said auxiliary generator, connected across the output of said main generator, 8. triode connected in the circuit of said field winding for the auxiliary generator, with its cathode in series with the main field winding, the series connection of said cathode and said main field winding being connected across the terminals of the main generator, a resistor connected across the output of said main generator, and a source of direct current potential variably connected by its positive terminal to said resistor, and connected by its negative terminal to the grid of said triode, to increase the sensitivity of current flow through the auxiliary field winding in response to variations of output of the main generator.

7. An electric installation comprising a main dynamo having an armature and an exciting winding connected in parallel therewith, an auxiliary dynamo mechanically coupled to said main dynamo, and a second exciting winding for the main dynamo energized by said auxiliary dynamo in such manner that its field counteracts the field of the first exciting winding, said auxiliary dynamo having an exciting winding and a circuit therefor comprising a triode, said triode having an anode, a cathode and a. grid, means for biasing said grid, a potentiometer connected across said main dynamo and having a sliding dynamo having an armature and an exciting winding therefor connected in parallel with said armature, a second exciting winding, an auxiliary dynamo mechanically coupled to the said main dynamo and supplying exciting current to said second exciting winding in such manner as to counteract the field created by the first winding, at least one triode, containing an incandescent cathode, a grid and an anode, an exciting circuit for the auxiliary dynamo and containing said anode and cathode, a potentiometer resistance connected across the terminals of the main dynamo and having a movable contact connected to the grid of the triode, means for biasing the grid of the triode, and a resistance through which the cathode is connected across the armature of the main dynamo.

' FRANS HENDRIK or: JONG. 

